Despite originating just 50 miles off the Texas coast, the ninth tropical depression of the season (TD#9) remarkably transformed itself into a hurricane --Humberto--before making landfall just 18 hours later. According to the National Hurricane Center (NC), this was the fastest that a tropical cyclone has ever developed just before landfall in the historical record.

TD#9 formed ahead of an old frontal boundary from a persistent area of low pressure in the western Gulf of Mexico at 15:00 UTC (10:00 am CDT) on the 12th of September 2007. This set of images was taken by the Tropical Rainfall Measuring Mission satellite, also known as TRMM. TRMM came into service in November of 1997. Designed to measure rainfall from space, from its low-earth orbit TRMM has proven itself to be a valuable platform for observing tropical cyclones in the Tropics. This first image was taken at 10:04 UTC (5:04 am CDT) 12 September just hours before TD#9 formed. It shows the horizontal pattern of rain intensities estimated from TRMM satellite data. Rain rates in the center swath are based on the TRMM Precipitation Radar (PR), and those in the outer swath on the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). Although still officially just a disturbance at the time, it is clear that the system is getting organized. Within the fairly coherent mass of rain, there are bands of moderate to heavy rain (green and red areas). Some of the bands show slight curvature, which is evidence of a circulation. The bulk of the rain lies just to the east of the center of circulation.

Eleven hours after the first image was taken, TD#9 was upgraded to a Tropical Storm and given the name Humberto. Humberto followed a northeastward track in the direction of the Texas-Louisiana border. The system continued to organize and rather quickly gained strength, reaching hurricane intensity by 05:00 UTC (midnight local time) on the 13th, just 8 hours after it had became a tropical storm. The next image was taken at 09:09 UTC (4:09 am CDT) on the 13th and shows Humberto immediately after it made landfall near the Texas-Louisiana border. An eye is now clearly visible surrounded by a ring of moderate intensity rain (green annulus). Bands with heavier rain (darker reds) are streaming ashore over the Louisiana coastline east of the center. At the time of this image, Humberto's maximum sustained winds were reported at 75 knots (86 mph) by NHC.

This last image was taken concurrent with the previous and shows a 3D view of Humberto as seen by the TRMM PR. Higher tops are shown in red. Areas of deep convection are occurring in the western eyewall (red area farthest to the left) and in the rainbands east of the center (red tops farthest to the right). After making landfall Humberto began to weaken. The system is expected to bring some much needed rain to the Southeast. So far, one person has died as a result of the storm.

Click to see a 3-D flyby animation courtesy of TRMM's Precipitation Radar data





Click to see a TRMM based (3B42) HURRICANE HUMBERTO Rainfall Accumulation animation ( Quicktime .9MB)

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Images and animations produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC)